The present invention relates to devices and methods for delivering, administering or dispensing substances, and to methods of making and using such devices. More particularly, it relates to devices and methods for metered administration of liquid products in biotechnology applications, preferably in medical applications, including veterinary and pharmaceutical applications. It relates in particular to infusion and injection appliances and devices, and methods of making and using such appliances and devices.
In various treatments, great importance is attached to the accuracy of the metering of products to be administered, for example in the administration of insulin in the treatment of diabetes. Infusion appliances and injection appliances are common in which a product to be administered is dispensed from a product reservoir by means of a motor-driven reciprocating piston pump in the case of infusion appliances or by means of a manually activated reciprocating piston pump in the case of injection appliances. In infusion appliances, the reciprocating piston is usually driven by a rotary drive mechanism, the rotation movement of the drive mechanism being converted by means of a spindle drive into the linear movement of the piston. In injection appliances, a spindle drive is often used for selecting the product dose to be administered, while the linear movement of the piston is effected directly by hand. In injection appliances, rack-and-pinion gears are also customary. A common feature of the above examples of appliances used for administration is that the accuracy of the metering depends critically on the degree of precision with which it is possible to predetermine the distance that the piston has to travel to deliver a defined dose of product.
Infusion appliances and injection appliances of the type mentioned above are described by DE 198 40 992 A, DE 198 22 031 C and DE 199 00 827 C, for example.
Particular demands on metering accuracy and precision have to be met by infusion appliances with which the product is often dispensed, delivered or administered over fairly long periods of time in small and discrete boluses or doses. Structural features serving in principle to improve the accuracy of the metering may at the same time also have a disruptive effect on, for example, the capacity for occlusion detection. An infusion appliance with advantageously configured, automatic occlusion detection is described in DE 198 40 992, to which reference is hereby made for the purposes of the present invention. A further appliance with occlusion detection is described in WO 01/72357 A2. For the occlusion detection, the entire delivery means is supported on the housing of the infusion appliance via a sensor. To ensure that this manner of support does not permit relative movements between the delivery means and the product container, WO 01/72357 A2 proposes, for assembly of the appliance, that the entire delivery means is first pressed in the delivery direction of the piston as far as an abutment formed by the housing, that the delivery means is then essentially relieved of the pressure, and finally that a closure cap is fitted into a rear opening of the housing and is adhesively bonded to the housing. The cap is intended to hold the delivery means in abutment against the housing. As an alternative configuration, it is also proposed that the delivery means, at its end remote from the piston, is supported on the rear base of the housing by means of an elastic sealing ring, and that a hollow space remaining between the rear face of the delivery means and the base of the housing is filled with a filler material, for example with silicone. The filler material should be substantially non-compressible, so as not to relieve the load on the sensor.